# US 12,015,995 B2 · Quasi co-location source selection and indication on sidelink > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,015,995 B2 - Document ID: US12015995B2 - Status: Granted - Kind: B2 - Application number: 17/137,083 - Filed: 2020-12-29 - Published: 2021-07-01 - Granted: 2024-06-18 - Earliest claimed: 2019-12-31 - Assignees: QUALCOMM Incorporated - Applicants: QUALCOMM Incorporated - Inventors: Sony Akkarakaran; Tao Luo; Ling Ding; Junyi Li; Jung Ho Ryu; Jelena Damnjanovic; Mahmoud Taherzadeh Boroujeni - Web page: https://patentgrep.com/patent/US12015995B2 ## CPC - H04B 7/088: {using beam selection} - H04W 72/02: Selection of wireless resources by user or terminal - H04B 7/06968: {using quasi-colocation [QCL] between signals} - H04W 56/001: {Synchronization between nodes} - H04W 72/046: {the resource being in the space domain, e.g. beams} - H04W 72/51: based on terminal or device properties - H04W 72/542: using measured or perceived quality - H04B: TRANSMISSION - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract Certain aspects of the present disclosure provide techniques for selecting and indicating a quasi colocation (QCL) source signal for sidelink (SL) communications. For example, a scheduling node may select from multiple candidates a signal for a first user equipment (UE) to use as a spatial QCL source for a receive (RX) or transmit (TX) beam to use for communicating with a second UE on a SL interface. The scheduling node may then signal the first UE an indication of the selection of the signal. ## Claims ### Claim 1 A method for wireless communications performed by a scheduling node, comprising: selecting, from multiple candidates based on one or more criteria, a signal for a first user equipment (UE) to use as a spatial quasi co-location (QCL) source for a receive or transmit beam to use for communicating with a second UE on a sidelink interface, wherein the multiple candidates comprise a first signal from the first UE to the second UE with a first signal quality and a second signal from the second UE to the first UE with a second signal quality, and wherein the one or more criteria indicate use of the first signal as the QCL source when the first signal quality is higher than the second signal quality or the second signal as the QCL source when the second signal quality is higher than the first signal quality; and signaling the first UE an indication of the selection. ### Claim 2 (depends on 1) The method of claim 1, wherein the scheduling node also signals the second UE an indication of the selection. ### Claim 3 (depends on 1) The method of claim 1, wherein the signal selected for the first UE comprises a reference signal or a channel. ### Claim 4 (depends on 1) The method of claim 1, wherein the candidates include at least one of: a first candidate for the first UE to use a signal transmitted from the first UE to the second UE as a QCL source for a receive beam for receiving a transmission from the second UE; or a second candidate for the first UE to use a signal transmitted from the second UE to the first UE as a QCL source for a transmit beam for sending a transmission to the second UE. ### Claim 5 (depends on 1) The method of claim 1, wherein the candidates include at least one of: a first candidate for the first UE to use a signal transmitted from the second UE to the first UE as a QCL source for a receive beam for receiving a transmission from the second UE; or a second candidate for the first UE to use a signal transmitted from the first UE to the second UE as a QCL source for a transmit beam for sending a transmission to the second UE. ### Claim 6 (depends on 1) The method of claim 1, wherein the scheduling node comprises the second UE or a base station. ### Claim 7 (depends on 1) The method of claim 1, wherein at least one of the criteria involves a difference in: a first sidelink channel quality measured based on a signal transmitted from the first UE to the second UE; and a second sidelink channel quality measured based on a signal transmitted from the second UE to the first UE. ### Claim 8 (depends on 7) The method of claim 7, wherein the scheduling node: indicates the first UE should use a signal transmitted from the first UE to the second UE as the spatial QCL source if the first sidelink channel quality is greater than the second sidelink channel quality; or indicates the first UE should use a signal transmitted from the second UE to the first UE as the spatial QCL source if the second sidelink channel quality is greater than the first sidelink channel quality. ### Claim 9 (depends on 1) The method of claim 1, wherein at least one of the criteria considers whether the first UE or second UE is currently, or has recently completed, beam sweeping transmissions on the sidelink. ### Claim 10 (depends on 9) The method of claim 9, wherein the scheduling node: indicates the first UE should use a signal transmitted from the first UE to the second UE as the spatial QCL source if the first UE is currently, or has recently completed, beam sweeping transmissions on the sidelink; or indicates the first UE should use a signal transmitted from the second UE to the first UE as the spatial QCL source if the second UE is currently, or has recently completed, beam sweeping transmissions on the sidelink. ### Claim 11 (depends on 1) The method of claim 1, wherein the candidates include: at least one candidate for the first UE to use a signal transmitted between the first UE and a reference node different than second UE as a QCL source for a receive beam or a transmit beam to communicate with the second UE. ### Claim 12 (depends on 11) The method of claim 11, wherein at least one of the criteria considers a relative position of the reference node, first UE, and second UE. ### Claim 13 (depends on 11) The method of claim 11, wherein the scheduling node comprises the second UE or the reference node. ### Claim 14 (depends on 1) The method of claim 1, wherein the scheduling node makes the selection based on measurement results received by the scheduling node: via at least one of radio resource control (RRC) signaling, a medium access control (MAC) control element (CE), physical uplink control channel (PUCCH), or physical uplink shared channel (PUSCH), if forwarded via a cellular interface; or via at least one of sidelink equivalents or similar signaling mechanisms as RRC signaling and a MAC CE, physical sidelink control channel (PSCCH), and physical sidelink shared channel (PS SCH), if forwarded via a sidelink interface. ### Claim 15 (depends on 1) The method of claim 1, wherein the scheduling node signals the first UE an indication of the selected option: via at least one of radio resource control (RRC) signaling, a medium access control (MAC) control element (CE), downlink control information (DCI), or physical downlink shared channel (PDSCH), if received via a cellular interface; or via at least one of sidelink equivalents or similar signaling mechanisms as RRC signaling and a MAC CE, physical sidelink control channel (PSCCH), and physical sidelink shared channel (PSSCH), if received via a sidelink interface. ### Claim 16 A method for wireless communications performed by a first user equipment (UE), comprising: receiving signaling from a scheduling node indicating a selection, from multiple candidates based on one or more criteria, of a signal for the first UE to use as a spatial quasi co-location (QCL) source for a receive or transmit beam to use for communicating with a second UE on a sidelink interface, wherein the multiple candidates comprise a first signal from the first UE to the second UE with a first signal quality and a second signal from the second UE to the first UE with a second signal quality, and wherein the one or more criteria indicate use of the first signal as the QCL source when the first signal quality is higher than the second signal quality or the second signal as the QCL source when the second signal quality is higher than the first signal quality; and communicating with the second UE on the sidelink interface with a receive or transmit beam determined based on the indicated selection. ### Claim 17 (depends on 16) The method of claim 16, wherein the signal selected for the first UE to use as a spatial QCL source comprises a reference signal or a channel. ### Claim 18 (depends on 16) The method of claim 16, wherein the scheduling node comprises the second UE or a base station. ### Claim 19 (depends on 16) The method of claim 16, wherein the signaling: indicates the first UE should use a signal transmitted from the first UE to the second UE as the spatial QCL source; or indicates the first UE should use a signal transmitted from the second UE to the first UE as the spatial QCL source. ### Claim 20 (depends on 19) The method of claim 19, wherein the candidates include at least one of: a first candidate for the first UE to use a signal transmitted from the first UE to the second UE as a QCL source for a receive beam for receiving a transmission from the second UE; or a second candidate for the first UE to use a signal transmitted from the second UE to the first UE as a QCL source for a transmit beam for sending a transmission to the second UE. ### Claim 21 (depends on 19) The method of claim 19, wherein the candidates include at least one of: a first candidate for the first UE to use a signal transmitted from the second UE to the first UE as a QCL source for a receive beam for receiving a transmission from the second UE; or a second candidate for the first UE to use a signal transmitted from the first UE to the second UE as a QCL source for a transmit beam for sending a transmission to the second UE. ### Claim 22 (depends on 16) The method of claim 16, wherein the candidates include: at least one candidate for the first UE to use a reference signal transmitted between the first UE and a reference node different than second UE as a QCL source for a receive beam or a transmit beam to communicate with the second UE. ### Claim 23 (depends on 16) The method of claim 16, wherein the scheduling node makes the selection based on measurement results transmitted from the first UE: via at least one of radio resource control (RRC) signaling, a medium access control (MAC) control element (CE), physical uplink control channel (PUCCH), or physical uplink shared channel (PUSCH), if forwarded via a cellular interface; or via at least one of sidelink equivalents or similar signaling mechanisms as RRC signaling and a MAC CE, physical sidelink control channel (PSCCH), and physical sidelink shared channel (PS SCH), if forwarded via a sidelink interface. ### Claim 24 (depends on 16) The method of claim 16, wherein the signaling from the scheduling node indicating the selection is received: via at least one of radio resource control (RRC) signaling, a medium access control (MAC) control element (CE), downlink control information (DCI), or physical downlink shared channel (PDSCH), if received via a cellular interface; or via at least one of sidelink equivalents or similar signaling mechanisms as RRC signaling and a MAC CE, physical sidelink control channel (PSCCH), and physical sidelink shared channel (PSSCH), if received via a sidelink interface. ### Claim 25 An apparatus for wireless communications performed by a scheduling node, comprising: a memory comprising instructions; and one or more processors configured, individually or in any combination, to execute the instructions and cause the scheduling node to: select, from multiple candidates based on one or more criteria, a signal for a first user equipment (UE) to use as a spatial quasi co-location (QCL) source for a receive or transmit beam to use for communicating with a second UE on a sidelink interface, wherein the multiple candidates comprise a first signal from the first UE to the second UE with a first signal quality and a second signal from the second UE to the first UE with a second signal quality, and wherein the one or more criteria indicate use of the first signal as the QCL source when the first signal quality is higher than the second signal quality or the second signal as the QCL source when the second signal quality is higher than the first signal quality; and signal the first UE an indication of the selection. ### Claim 26 (depends on 25) The apparatus of claim 25, wherein the candidates include at least one of: a first candidate for the first UE to use a signal transmitted from the first UE to the second UE as a QCL source for a receive beam for receiving a transmission from the second UE; or a second candidate for the first UE to use a signal transmitted from the second UE to the first UE as a QCL source for a transmit beam for sending a transmission to the second UE. ### Claim 27 (depends on 26) The apparatus of claim 26, wherein the candidates include at least one of: a first candidate for the first UE to use a signal transmitted from the second UE to the first UE as a QCL source for a receive beam for receiving a transmission from the second UE; or a second candidate for the first UE to use a signal transmitted from the first UE to the second UE as a QCL source for a transmit beam for sending a transmission to the second UE. ### Claim 28 An apparatus for wireless communications performed by a first user equipment (UE), comprising: a memory comprising instructions; and one or more processors configured, individually or in any combination, to execute the instructions and cause the first UE to: receive signaling from a scheduling node indicating a selection, from multiple candidates based on one or more criteria, of a signal for the first UE to use as a spatial quasi co-location (QCL) source for a receive or transmit beam to use for communicating with a second UE on a sidelink interface, wherein the multiple candidates comprise a first signal from the first UE to the second UE with a first signal quality and a second signal from the second UE to the first UE with a second signal quality, and wherein the one or more criteria indicate use of the first signal as the QCL source when the first signal quality is higher than the second signal quality or the second signal as the QCL source when the second signal quality is higher than the first signal quality; and communicate with the second UE on the sidelink interface with a receive or transmit beam determined based on the indicated selection. ### Claim 29 (depends on 28) The apparatus of claim 28, wherein the candidates include at least one of: a first candidate for the first UE to use a signal transmitted from the first UE to the second UE as a QCL source for a receive beam for receiving a transmission from the second UE; or a second candidate for the first UE to use a signal transmitted from the second UE to the first UE as a QCL source for a transmit beam for sending a transmission to the second UE. ### Claim 30 (depends on 28) The apparatus of claim 28, wherein the candidates include at least one of: a first candidate for the first UE to use a signal transmitted from the second UE to the first UE as a QCL source for a receive beam for receiving a transmission from the second UE; or a second candidate for the first UE to use a signal transmitted from the first UE to the second UE as a QCL source for a transmit beam for sending a transmission to the second UE.